The Supreme Court will decide whether extra public funds may be given to state candidates who forgo private fundraising and who are facing wealthy, free-spending individuals.

Reporting from Washington — The Supreme Court announced Monday it would hear a challenge to Arizona's public funding of state campaigns, setting the stage for a ruling that could doom efforts to limit the effects of private money in elections.

The court's decision next year will be the latest in a series of rulings on campaign funding laws, in which the conservative majority has struck down both state and federal laws while saying that free speech calls for free spending in politics. In January, the justices struck down the 63-year-old federal law that barred businesses and unions from funding election ads.

Good-government reformers have held out hope that taxpayer funding of campaigns could keep candidates focused on the interests of ordinary voters, rather than on the special interests of their big donors. But that option seems increasingly in doubt.

In June, the Supreme Court temporarily blocked Arizona from giving additional public funds to state candidates, including Gov. Jan Brewer, who had agreed to forgo private fundraising and who were facing free-spending rivals.

Arizona's voters adopted the Clean Elections Act in 1998 after a scandal that featured state legislators caught on video stuffing campaign cash into gym bags. Candidates who opt for the public funding are entitled to extra matching funds if they are being outspent by their private-funded opponents.

But two years ago, the Supreme Court struck down a similar provision in the McCain-Feingold Act. The "millionaire's amendment" allowed candidates for Congress to accept larger contributions if they faced a wealthy, self-financed opponent. In a 5-4 decision, the high court said the provision was "a drag" on the 1st Amendment rights of wealthy, free-spending candidates.

That ruling, in turn, fueled a constitutional challenge to Arizona's law. "The matching funds system brazenly violates the 1st Amendment rights of candidates to speak without having government put its thumb on the scale of their opponents," said Clint Bolick, a lawyer for the Goldwater Institute, a Phoenix think tank.

The lawyers challenging the Arizona law said Maine and Connecticut had also adopted public funding laws for state candidates. They cited six other states — Florida, Hawaii, New Mexico, North Carolina, West Virginia and Wisconsin — that offered public funding for some state offices, including for judges who ran for election. Some of these states could be affected by a ruling.

"The court should put an end to public financing schemes like Arizona's that are aimed at suppressing free speech," said Bill Maurer, a lawyer for the Virginia-based Institute for Justice, which filed a separate suit.

The justices said Monday they had voted to hear the pair of challenges to the Arizona law. Arguments will be heard in March, and a decision will be handed down by summer.

Rick Hasen, an election law expert at Loyola Law School in Los Angeles, said the "continued demise of public financing of campaigns" was likely to be the big story in the year ahead. "Serious candidates will not opt into a public financing system," he said, if they can be vastly outspent by a well-funded opponent.

The New York-based Brennan Center for Justice, which called Arizona's law a model for other states, emphasized that the law put no limits on how much privately funded candidates could raise and spend.

"This law has boosted speech while combating corruption," said Michael Waldman, the group's executive director.

Other advocates of public funding said that a ruling striking down the "matching funds" provision in the Arizona law would not void all laws that offered tax money to candidates.

The Arizona cases will be heard as one. They are Arizona Free Enterprise Club's Freedom Club PAC vs. Bennett and McComish vs. Bennett.

The court took no action Monday on several closely watched cases, including Wal-Mart's appeal of a ruling that allowed a sex-bias lawsuit to proceed as a class action representing 1.5 million women.